In war and other forms of politics, what a difference a day makes. On Friday, Col. Muammar al-Qaddafi’s forces were en route to destroy the rebellion in Benghazi, with the “brother leader” himself vowing to show “no mercy, no pity” towards those foolhardy enough to challenge his 42-year rule. “We will come house by house, room by room,” he warned. “It’s over.”

Then suddenly, Qaddafi’s foreign minister was begging for a cease-fire.

Jeffrey White, a military intelligence veteran now at the Washington Institute for Near East Policy, called Qaddafi’s cease-fire declaration a “cynical ploy” since Qadaffi’s forces were still reported to be engaged in heavy fighting on Friday in at least three towns, among them, Misurata, Libya’s third largest city. “Nobody’s falling for it,” said White.

But Washington’s belated support for the no-fly zone and President Obama’s statement on Friday that America would join France, Britain, other NATO and Arab League allies in imposing a no-fly zone to stop the violence is a game-changer. And Qaddafi has clearly gotten the message.

So what happened? After days of deadly dithering, the United Nations Security Council stood up to the bellowing bully of a dictator. Late Friday night, the U.N. redeemed itself by approving a resolution that provided not only for a “no-fly zone” over Libya to ground Qaddafi’s mercenary-flown planes and choppers, but authorized member states to take “all necessary measures” short of sending in ground forces to prevent Qaddafi from slaughtering his own people.

Within a day, the resolution that some of us had been urging for weeks had worked its magic, without a shot yet to be fired. The bellowing bully of the desert was suddenly cowed, his threats exposed as hollow.

Here’s what’s happened so far. First of all, the United Nations’ stature has been temporarily restored. With its majority vote, the Security Council showed that it was not inevitably destined to be merely a forum for endless babble and toothless rhetoric. It could occasionally do more than growl; it could actually roar.

Second, the Obama administration was also saved from its own indecisiveness. Its inaction prompted the Arab League, another forum usually known for endlessly lavish and ineffectual meetings, to call for a no-fly zone over Libya, and in Europe, for France, of all countries, to lead the charge to prevent Qaddafi from butchering his citizens. France’s new foreign minister, Alain Juppe, begged the council to act in a dramatic appearance on Thursday night. “"We have very little time left, a matter of days, if not hours," Juppe pleaded just before the vote. Every hour, he said, “raises the weight on our shoulders. We should not arrive too late."

Being charitable, one could argue that this is what White House press secretary Jay Carney intended when he said on Tuesday that any American action “should be done in concert with our international partners.”

Or one could argue that Obama hesitated after demanding that Qaddafi step down because he started listening to the chorus of foreign policy experts who warned that a no-fly zone would never work, and that it risked drawing the United States into another war in a Muslim country. Or perhaps, ever the politician, he was watching the polls which said that almost three quarters of Americans surveyed last week in a CNN/Opinion Research Corporation poll said that America should "leave it to others" to try to solve the conflict in Libya.

But by Thursday afternoon, the risk of a slaughter in Benghazi had finally spurred the administration out of its caution bordering on paralysis. Yet another shift in American policy was heralded by Secretary of State Hillary Clinton, who has often been tougher on national security calls than her Hamlet-like boss. Speaking in Tunis on Thursday, she said that there was now no choice but to act. “If you don’t get him out and if you don’t support the opposition and he stays in power, there’s no telling what he will do.” And yes, she warned, he would do “terrible things,” because it was just “in his nature.”

Whether Washington was dithering or indecisive, the outcome, at least so far, seems positive. The bully has backed down, for the moment. But there are real challenges ahead.

As Marc Ginsberg, the former U.S. ambassador to Morocco, suggested, has Qaddafi called for a cease-fire just to “forestall a foreign military attack on his paltry air defenses and ground forces on Benghazi’s outskirts?” Will the allies accept a “painful stalemate” hoping that other UN sanctions will grind him down and cause more tribes to turn on him? Will the resolution ultimately result in “regime change” or will the coalition that voted the no-fly zone and the Libyan rebels fighting on the ground, for that matter, splinter over tactics and goals?

There are also hard choices ahead for Obama. Libya may now at last be a clear call, if only on humanitarian grounds, but what will the White House do about Bahrain, whose Sunni Muslim ruling family seems determined to kill protesters if it must to retain power in a country whose population is overwhelmingly Shiite? What about Saudi Arabia, where demonstrations have so far been relatively small and confined largely to the eastern Shiite Muslim province of the kingdom. Should oil-rich nations be permitted to kill their citizens with impunity to suppress protests when such conduct in Tunisia, Egypt, and Libya is denounced by President Obama as “outrageous” and “on the wrong side of history”?

Will Americans see the emergence of a consistent standard or policy from their president, or an opportunistic alliance with whoever appears to be winning the battle for the hearts and minds of the Arab street? Is there now or will there ever be an “Obama doctrine” on this issue that reflects both American values and what we have learned from the last decade of divisive wars?